This invention relates to an improved method for installing a pressure roller and an improved load arm configuration to ensure that the pressure roller is installed in proper engagement with the load arms.
In the production of copies by electrophotographic processes, a continuous loop of photoconductor film is commonly used. This photoconductor film is charged initially, in a primary charging section thereafter passed to an imagining section, a developing section, and an image transfer section where a toner image on the photoconductor film is transferred to a paper or other transfer surface to produce a copy of the toner image on the paper or other transfer surface. The paper is subsequently passed to a fuser section where the toner image on the paper is fixed to the paper by elevated pressure and temperature. The photoconductor film then passes through a neutralization section and thereafter past a brush cleaner which removes contaminants from the film prior to passing the photoconductor film back through the primary charging section.
In the fuser section, typically a pressure roller is in contact with a fuser roller to subject the paper bearing the toner image to temperature and pressure to fix the toner image on the paper. As well known to those skilled in the art, the fuser roller may be heated directly or indirectly. Further either the fuser roller or pressure roller may be directly or indirectly driven to rotate the two rollers.
The pressure imposed on the fuser roller is imposed typically by imposing a pressure on the pressure roller. This pressure is created by load arms, which impose the pressure load on the pressure roller. Typically the load is about 325 to about 375 pounds. Typically two load arms are used, one of each end of the fuser roller.
In some embodiments it has been found that the load arms have been improperly placed in engagement with pressure roller bearing surfaces on the pressure roller. This misalignment is a result of positioning the pressure roller in a slightly out of alignment position. As a result of this misalignment, the load arms can be placed in engagement with spacer washers, which are positioned on the ends of the pressure roller to maintain pressure roller bearing surfaces at a desired position relative to the pressure roller. The positioning of the pressure roller in a slightly out of alignment position results in the load arms engaging the washers on the pressure roller on one side and only partially engaging the pressure roller bearing surfaces on the other side of the pressure roller. This misalignment can cause many problems in operation, in the closing of a cooler section, which is rotatably closable over the lower portion of a fuser section and the like. The difficulty in properly installing the pressure roller is in part due to its inaccessibility since cooler sections are designed to open by only about 70 degrees from the lower portion of the fuser section.
Accordingly, a continuing effort has been directed to the development of improved load arm configurations and improved methods for installing the pressure roller to avoid the misalignment of the load arms with the pressure roller bearing surfaces.
According to the present invention, it has been found that improved reliability is achieved in a copier/duplicator machine having a pressure roller system including two load arms for engagement with pressure roller bearing surfaces on each end of a pressure roller wherein the load arms include locator plates positioned on their outsides and extending beyond an engagement surface on each load arm and toward and past the pressure roller bearing surfaces to restrict the positioning of the load arm engagement surfaces so that the load arms can be installed only in proper engagement with the pressure roller bearings on the ends of the pressure roller.
The invention further comprises a load arm system for a copier/duplicator machine for applying pressure to a pressure roller having pressure roller bearings positioned on its ends, the pressure roller bearings having pressure roller bearing engagement surfaces, the system comprising: two load arms each having a first and a second end and being retained in a fixed spatial relationship to each other, each having a load arm engagement surface configured for engagement with the pressure roller bearing engagement surfaces at their first ends, and rotatably connected at their first ends to the machine for rotation of the load arm engagement surfaces into engagement with the pressure roller bearing engagement surfaces; a pressure source in operative contact with the second ends of the load arms and adapted to apply a selected pressure to the pressure roller by applying a selected pressure to the second ends of load arms; a locator plate positioned on the outside of the first ends of the load arms and extending past the load arm engagement surfaces and the pressure roller bearing engagement surfaces so that when the load arms are installed with the locator plates outside the pressure roller bearing engagement surfaces the pressure roller and load arms are properly positioned.
The invention still further comprises a method for installing a pressure roller in a copier/duplicator machine in proper orientation to load arms rotatably connected to the machine, the method comprising: configuring a machine cooler section openable by rotary movement relative to a lower fuser unit section for rotary movement to an open position wherein the cooler section is rotated to an angle greater than 70 degrees relative to the lower fuser section thereby providing improved access to the lower fuser section for installation of a pressure roller; positioning the pressure roller in a pressure roller receptacle in the lower fuser section of the machine; positioning locator plates on the load arms so that the load arms can be moved into engagement with the pressure roller only when the load arms are in proper alignment with pressure roller bearing surfaces on the pressure roller; and, moving the load arms into properly aligned engagement with the pressure roller bearing surfaces.